Brightness enhancing films (BEF) have been used in lighting panels for directing light from lighting fixtures through luminaires and laptop computers displays. The brightness enhancing films, which can have linear prisms, diffuse light with a desired directionality. Often the films have been used in combination with a fluorescent light source. The films have had partial success in improving luminair or display brightness by controlling the angle at which light emerges. However, a need still exists for improved control of lighting and enhancement of brightness for laptop computer screens.
The present invention includes a light collimating film having a sheeting having a first side and a second side, wherein the first side includes a series of prisms, and the second side includes a plurality of subwavelength structures. In a preferred embodiment, the prisms have an included angle in the range of between about 60 and 120 degrees.
In another embodiment, the invention includes a back lighting display device having a lighting means, a display panel, and a sheeting having a first side and a second side, wherein the first side includes a series of prisms, and the second side includes a plurality of subwavelength structures.
In a further embodiment, the invention includes a back lighting display device having a first collimating film having a first surface with subwavelength structures thereon and a second surface with linear prisms having an included angle of greater than about 95 degrees, and a second collimating film having a first surface with a moth-eye structure thereon and a second surface with linear prisms having an included angle of less than about 85 degrees.